Scalable method for encoding a series of original images, and associated image encoding method, encoding device and decoding device

ABSTRACT

A series of decoded images is generated from a series of original images encoded by a first encoding technique following movement-compensated, predictive encoding, where a starting image of a group of successive original images that are to be encoded is defined by a second encoding technique following movement-compensated, temporally filtered partial band encoding based on a determined encoding property of a decoded image of the group of images that are to be encoded, the decoded image is used for generating an output image having a low resolution level, before the images are encoded. At least one output image is generated on each level of resolution from the successive original images of the group of from at least one decoded image during image encoding. The decoded images are provided only with a reduced quality while the reconstituted images are of great quality.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and hereby claims priority to GermanApplication No. 10 2004 031 407.1 filed on Jun. 29, 2004, the contentsof which are hereby incorporated by reference.

BACKGROUND

As described by K. Hanke's description of “3D-videocodierung” at thewebsite for the Institut für Nachrichtentechnik at Rheinisch-WesfälischeTechnische Hochschule-Aachen, video encoding methods exploit specificsignal properties for efficient encoding of a succession of images. Insuch cases spatial and temporal dependencies between the individualimages or the pixels of these images are exploited. The better an imageencoding or video encoding method is able to exploit these dependenciesbetween the individual images or pixels, the greater in general is acompression factor which can be achieved.

A basic distinction is made in current methods for video encodingbetween hybrid encoding methods, such as the video coding standardsITU-T H.263 “Videocoding for Low Bitrate Communication”, February 1998or ITU-T H.264 “Advanced Video Coding for Generic Audio VisualServices”, May 2003, for example, and so-called three-dimensionalfrequency encoding approaches. Although both methods attempt to encodethe video signal, which consists of the succession of images, bothspatially and also temporally, with hybrid encoding methods use is madeinitially of a movement-compensated prediction in the temporal directionand subsequently of a two-dimensional transformation of a differenceimage created, such as with the aid of a two-dimensional Discrete CosineTransformation (DCT) for example, to enable a spatial correlationbetween adjacent pixels within the difference image to be removed.

With the three-dimensional frequency encoding approaches, such as themovement-compensated, temporally filtered partial band encoding forexample, by contrast with the hybrid encoding methods, no temporalprediction but a “true” transformation in the direction of the time axisis performed, in order to thereby exploit the temporal correlation ofconsecutive images. With such partial band encoding the succession ofimages is encoded into a number of “temporal” frequency bands before thespatial two-dimensional decorrelation, such as with two frequency bandsin a high and a low frequency band for the temporal high-frequency andlow-frequency image components. In the fragmentation of the spectrum thedistribution of the frequencies occurring in these frequency bands isheavily dependent on the size of the movement occurring in the videosignal. Provided the observed video signal does not feature any movingor modified elements, all high-frequency “time spectrum components” areequal to zero and the total energy is concentrated on the partialfrequency band. Normally however a change in an image over time willalways be able to be seen in a succession of images, such as a localobject displacement for example, a change of object size or a change ofscene. This leads to a distribution of energy to a number of spectralcoefficients, with high-frequency components also being produced.

To reduce the spectral components in the temporal high-frequency bandand thus to concentrate the energy on the temporal low-frequency band,before the temporal filtering of the video signal into a number of“temporal” frequency bands, a movement estimation and a movementcompensation of the images to be temporally filtered are undertaken.

According to H. Schwarz, D. Marpe and T. Wigand, Fraunhofer Institut fürTelekommunikation, Heinrich Herz Institut, “Scalable Extension ofH.264/AVC”, ISO/IEC JTC1/SC29/WG11, MPEG04/M10569/S03, March 2004, themovement-compensated, temporally-filtered partial band encoding can alsobe used for adjusting a scalable video data stream. For example atemporal, a qualitative or also a spatial scalability is enabled in thisway. Furthermore a combined scaling is presented in Chapter 3.2.4 ofSchwarz et al. In this case two different basic qualities (L0, L1) areobtained with the aid of the hybrid encoding method. To achieve improvedimage qualities additional scaled video data streams are included, suchas L2, L3, L4 and/or L5 for example. These additional scaled video datastreams (L2, . . . , L5) are created in Schwarz et al. with the aid of amovement-compensated, temporally filtered partial band encoding. Thus itis known that a scalable video data stream can be created with the aidof a first encoding method following movement-compensated, predictiveencoding and a second encoding method following movement-compensatedtemporally filtered partial band encoding.

SUMMARY

Described below are a method for image encoding and decoding, anencoding as well as a decoding device which allows image encoding andimage decoding of a succession of original images with amovement-compensated, temporally filtered partial band encoding methodwith the assistance of a movement-compensated predictive encoding methodin a simple and efficient manner.

With the method for encoding a group of successive original images, agroup of successive decoded images is created from the group ofsuccessive original images with the aid of a first coding method, whichis based on a motion-compensated, predictive coding, before the imageencoding of an image group of consecutive original images by a secondcoding method, which is based on a motion-compensated, temporallyfiltered subband coding, a start image of the image group being definedbased on an identified encoding property of one of the decoded images,which is used for generating an output image having a lower resolutionof the image group, with at least one output image being generated ateach resolution level by the image encoding of the consecutive originalimages of the image group and of at least one of the decoded images.

Through the described method for image encoding, in the encoding of theoriginal images by the second encoding method, the determined encodingproperties of the decoded images which are created by the first encodingmethod are taken into account. In this way the compressioncharacteristic, such as the compression rate for example, or the imagequality if the compression rate remains the same, is improved for thesecond encoding method.

Furthermore, by a suitable choice of start image for the image encodingby the second encoding method, the susceptibility to errors (errordrift) of image information created by the second encoding method isreduced and thereby the image quality is enhanced.

Furthermore the described method makes possible random access toindividual images which have been created after the first and/or secondencoding method.

Preferably the start image is defined on the basis of the decoded imageused, if an evaluation of the encoding property shows that at least oneimage block of the used decoded image was INTRA coded. Since an INTRAcoded image block is often encoded in higher image quality and no errordrift occurs in the INTRA coded image block, a reduced signal energy isthus achieved for at least one part of the image of the starting imageof the lower resolution level and through this an improved compressionproperty is made possible. An error drift does not occur, since with theINTRA coding no prediction from predecessor images takes place andthereby no errors can be transferred.

Alternately the start image is defined on the basis of the used, decodedimage, if an evaluation of the encoding property shows that a definednumber of image blocks of this used, decoded image were INTRA coded. Inthis way an increase in the compression efficiency of the secondencoding method is achieved, since a number of image parts of the outputimage of the low resolution level exhibit a low signal energy and cantherefore be encoded efficiently.

Alternately the start image is defined on the basis of the used, decodedimage if an evaluation of the encoding properties is that all imageblocks of this used, decoded image were INTRA coded. In this way a largeincrease in the compression efficiency of the second encoding method isachieved, since all image parts of the output image of the lowresolution level exhibit an especially low signal energy and cantherefore be compressed very efficiently.

Preferably a number of consecutive original images of the image group tobe encoded are adjusted as a function of the encoding propertydetermined. The result of this is that the number of consecutiveoriginal images of the image group can be set such that the decodedimage which can be assigned for setting of a difference image for theoutput image of the low resolution level is that image which has a verylow signal energy to be encoded.

If at least one intermediate image (Z1, Z2, Z3) is furthermore createdat each resolution level (R1, R2) and the intermediate images and theoutput image of the low resolution level are compressed, a reduction ofthe data volume of the intermediate images and of the output image ofthe low resolution level is achieved. If in addition compression isundertaken in accordance with a wavelet-based transformation, thisachieves an especially efficient reduction of the data volume of theintermediate images and of the output image of the low resolution level.

Also described is an image decoding method for decoding at least oneimage encoded by the method for image encoding. The result of this isthat both the encoded images of the first encoding method and also theintermediate images and the output image of the low resolution level ofthe second encoding method, which were created In accordance with themethod for image encoding, can be decoded.

Also described is an encoding device for encoding a succession oforiginal images. This makes it possible to execute the method for imageencoding in a device such as a mobile telephone for example.

Also described is a decoding device for executing the image decodingmethod. This enables the image decoding method to be executed in adevice such as a mobile telephone for example.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and advantages will become more apparent andmore readily appreciated from the following description of the exemplaryembodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a schematic diagram of an encoding of a succession of originalimages, which are compressed by a first encoding method following amovement-compensated, predictive encoding and which are encoded by asecond encoding method following a movement-compensated temporallyfiltered partial band encoding taking into account the decoded images ofthe first encoding method;

FIG. 2 is a more detailed diagram of the setting of an intermediateimage and of an output image using the second encoding method, which aregenerated in a number of processing steps within the first resolutionlevel from two input images, with a decoded image of the first encodingmethod being taken into account in the creation;

FIG. 3 is a schematic diagram of the processing steps within the lowresolution level, with an intermediate image and an output image beingcreated using two input images and two decoded images;

FIG. 4 is a schematic diagram of an encoding device, a decoding deviceand a transmission medium to execute the described method; and

FIG. 5 is a schematic diagram of the compression of a succession oforiginal images with a first and a second encoding method, with a numberof image groups each with a different number of original images to beencoded being compressed by the second encoding method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the exemplary embodiments,examples of which are illustrated in the accompanying drawings, whereinlike reference numerals refer to like elements throughout.

FIG. 1 shows an exemplary embodiment of the method described below. Asillustrated therein, a succession of original images O1, . . . , ON areto be compressed using a first encoding method CV1 and a second encodingmethod CV2. These original images O1, . . . , ON were for examplecreated by a camera K and will be provided in the color format with abrightness component Y and two chrominance components CR, CB in an imagesize with 640×480 pixels. Furthermore the original images O1, . . . , ONcan be subjected before their encoding to image processing, such asnoise suppression or edge sharpening for example.

First of all the first encoding method CV1 carries out amovement-compensated, predictive encoding of the original images O1, . .. , ON. These types of movement-compensated, predictive encoding methodsare known from S. Jun, S. Huifang, “Image and Video Compression forMultimedia Engineering”, CRC Press, 2000, such as the ITU-T H.263standard for example. With this standard encoded images B1, . . . , BMcan be created from the original images O1, . . . , ON using an INTRAcoding mode and/or an INTER coding mode. The INTRA coding mode encodesindividual image blocks of the relevant original image O1, . . . , ONwithout taking account of other original images O1, . . . ON. Bycontrast, in the INTER coding mode, individual image blocks of therelevant original image O1, . . . , ON are compressed, taking intoaccount one or more already encoded images B1, . . . BN. In addition itis advantageous, in the INTER coding mode, to carry out an estimation ofthe movement of the image block of the original image O1, . . . , ON tobe encoded and then only to encode this image block after a movementcompensation. Methods for estimating movement or compensating formovement are known from Jun et al. Furthermore the number M of theencoded images B1, . . . , BM can deviate from the number N of theoriginal images O1, . . . , ON, since for example not all originalimages O1, . . . , ON will be encoded.

Next, a succession of decoded images D1, . . . DM are created from theencoded images B1, . . . , BM with the aid of the first encoding methodCV1 Furthermore, for each decoded image D1, . . . , DM a separatedecoding list can be created, which specifies which image blocks of therelevant decoded image D1, . . . , DM have been encoded with the INTRAcoding mode and which with the INTER coding mode. These decoded imagesD1, . . . , DM are taken into account in the subsequent processing stepsby the second encoding method CV2. For the exemplary embodiment shown inFIG. 1 those decoded images D1, . . . , DM for which all image blockswere created with the INTRA coding mode are marked “I” and those forwhich at least one image block was encoded with the aid of the INTERcoding mode are marked “P”.

In a subsequent step all consecutive original images O1, . . . , ON of arelevant image group GOP are encoded with the aid of the second encodingmethod CV2. In the present exemplary embodiment three different imagegroups GOP1, GOP2, GOP3 can be seen. In this case the number of theoriginal images of the second image group GOP2 to be encoded has beenselected as four. The number of original images to be encoded per imagegroup GOP can vary, e.g. first of all two, then four and then eightoriginal images are encoded in the relevant image group GOP1, GOP2,GOP3. Thus for example the first original image of the second imagegroup GOP2 to be encoded is the third original image O3. The firstoriginal image of a respective image group GOP in each case is referredto below as the start image BSP.

Within the framework of this disclosure, a movement-compensated,temporally filtered partial band encoding method is to be seen as anencoding method in which, at a number of resolution levels, at least oneoutput image in each case is created from at least two input images. Inaddition intermediate images can also be created. The relevantintermediate image represents the movement-compensated components of theassociated input images of a first partial band. The relevant outputimage includes the movement-compensated component of the associatedinput images of a second partial band. The first partial band includesfor example the high frequency and the second partial band thelow-frequency components. At each lower resolution level at least twooutput images of the higher resolution become the input images.

The second encoding method CV2 depicted in FIG. 1 shows within thesecond image group GOP2 of two resolution levels R1, R2. In the firstresolution level R1 an intermediate image Z1, Z2 and an output image A1,A2 respectively are created from two input images E1 and E2, E3 and E4and the two associated decoded images D4, D6. The two output images A1,A2 are used as input images E5, E6 of the next resolution level R2. Atthe second resolution level R2, which in this exemplary embodimentcorresponds to the lower resolution level, a third intermediate image Z3and a third output image A3 are created from the input images E5, E6together with the decoded images D3, D5. In this exemplary embodimentthe low resolution level R2 simultaneously represents a lowestresolution level. The lowest resolution level can be seen as thatresolution level which generates only one output image within the imagegroup GOP. The functioning of the relevant resolution levels R1, R2 isexplained in greater detail by examples which refer to FIG. 2 and FIG.3.

FIG. 2 shows two input images E1, E2 which correspond to the originalimages O3 or O4. The second input image E2 is subdivided into a numberof image blocks Q1, . . . , Q9 for example. These image blocks Q1, . . ., Q9, which for example correspond to the macro blocks known from Jun etal., can have 16×16 pixels. Initially the second encoding method CV2carries out a movement estimation on the first input image El for atleast one image block Q1, . . . , Q9 of the second input image E2, e.g.for image block Q5, Possible strategies for performing the movementestimation are known from Jun et al. If a matching image area was foundin the first input image E1, this found image area is temporallyhighpass filtered after a movement compensation MC with the image blockQ5 of the second input image E2, for example by subtraction of therelevant pixels. The movement vectors found are summarized in a firstmovement vector list ML1.

If no good movement estimation is found for an image block Q1, . . . ,Q9, then for this image block Q1, . . . , Q9 for temporal lowpassfiltering, a corresponding image block R1, . . . , R9 can be includedfrom the decoded image D4 belonging to the second input image E2. Forexample no suitable image area has been found for the image block Q6 inthe first input image E1, so that the image block R6 of the fourthdecoded image D4 is filtered with the image block Q6 of the second inputimage E2.

Thus a first intermediate image Z1 is produced by temporal highpassfiltering. The result of the additional use of the fourth decoded imageD4 for the setting of the first intermediate image Z1 is that the firstintermediate image Z1 has less signal energy and thus a highercompression rate or, if the compression rate remains the same, a higherimage quality can be achieved by a subsequent compression method, suchas a wavelet-based transformation for example.

In a subsequent step the first output image A1 is created step-by-step.To this end the respective image blocks of the first intermediate imageZ1, which have been created with the aid of the first input image E1,are temporally lowpass filtered with the first input image E1 using aninverse movement compensation IMC (ML1), which takes account of themovement vectors of the first movement vector list ML1. The temporallowpass filtering can be executed by addition of the relevant pixels ofthe inverse movement-compensated image block of the first output imageZ1 and image block of the first input image E1. The first output imageA1 contains the “temporal” lowpass components of the input images E1,E2. The second output image A2 is created in the equivalent manner fromthe input images E3 and E4. In this case a second movement vector listML2 is generated.

In the present exemplary embodiment the procedure for executing themethod has been explained on the basis of images with 3×3 image blocks.In general there can be any number of image blocks, such as for example4×4, 8×9 or 11×9. In addition the number of image blocks of the decodedimages and of the input images can differ.

The individual processing steps of the second resolution level R2, whichcorresponds to the lower resolution level, are explained in greaterdetail below with the aid of FIG. 3. With the aid of the fifth and sixthinput image E5, E6, which correspond to the first and second outputimage A1, A2 of the preceding resolution level R1, and using the decodedimage D5 belonging to the sixth input image E6, the third intermediateimage Z3 is created after a movement estimation and movementcompensation MC (ML3). In this case a third movement vector list ML3 isgenerated. Furthermore, after an inverse movement compensation IMC (ML3)and taking into account the third input image E3, the provisional thirdinput image A3V is created. The third intermediate image Z3 includes thehigh-frequency components of the temporally filtered input images E5,E6. Furthermore the provisional third output image A3V includes thelowpass components of the temporally filtered input images E5, E6. Ifthe resolution levels R1, R2 are considered jointly, the provisionalthird output image A3V represents the “temporal” lowpass components ofthe second image group GOP2 of consecutive original images O3, O4, O5,O6. In an additional processing step, prediction, such as pixeldifferentiation of the provisional third output image A3V and of theassociated third decoded image D3 for example, is used to create thethird output image A3.

This third output image A3 and the intermediate images Z1, Z2, Z3 can becompressed before transmission to a decoding device DV, such as by awavelet transformation for example.

In accordance with the exemplary embodiment shown in FIG. 1, theassignment of the start image BSP for the image encoding has beenselected according to the second encoding method CV2 such that imagethis corresponds to the third original image O3. Since the number oforiginal images O3, . . . , O6 of the second image group GOP2 to beencoded in the present exemplary embodiment has been selected as four,the original images O3, O4, O5, O6 will be jointly encoded. After theircompression the next four original images, beginning with the seventhoriginal image O7, can be compressed in accordance with the secondencoding method CV2. This can be continued through to the end of thesuccession of original images O1, . . . , ON to be encoded. However thesecond encoding method CV2 can also combine more or fewer consecutiveoriginal images O1, . . . , ON into an image group GOP for encoding.

According to the method, before image encoding by the second encodingmethod CV2, following a movement-compensated, temporally filteredpartial band encoding, the start image BSP of an image group GOP ofconsecutive original images O1, . . . , ON to be encoded is defined onthe basis of a determined encoding property of a decoded image D3 usedto create an output image A3 of the lower resolution level R2 of thisimage group GOP to be encoded. Since the image quality of the outputimage of the lower resolution level, in the exemplary embodiment this isthe third output image A3 of the second resolution level R2, depends onthe associated decoded image, such as the third decoded image D3 forexample, the image quality of the associated decoded image is ofconsiderable importance. The image quality of the associated decodedimage essentially depends on the encoding property to which this decodedimage was subjected during its creation by the first encoding methodCV1. Thus by the selection of the start image BSP of the image groupGOP, such as of the second image group GOP2, depending on the encodingproperty of the decoded image used for the output image of the lowerresolution level, the image quality of the output image of the lowerresolution level is significantly influenced. With an optimum selectionof the start image BSP for the image group GOP an image with lowersignal energy is generated for example for the third output image A3which can be compressed very efficiently.

The encoding property can be determined by evaluation of the decodinglist belonging to the decoded image in each case. Furthermore theencoding property is also obtained by analysis of the encoded imagebelonging to the decoded image. Thus for example the image blocks MB1 inthe first decoded image D1 which were compressed by the INTRA or theINTER coding can be determined from analysis of the first encoded imageB1.

In addition the start image BSP is defined on the basis of the decodedimage used, e.g. D3, if an evaluation of the encoding property showsthat at least one image block MB1 of this used, decoded image D3 wasINTRA coded. An image block MB1 is for example to be understood as animage area consisting of 16×16 pixels. Since the INTRA coded image blockMB1 is typically subjected to a lower quantization than would be thecase if this image block MB1 were to have been INTER coded, a higherimage quality is produced for the image block MP1 of the decoded imageD3 used than is produced with an INTER coding. Thus for the third outputimage A3 a differential image with lower signal energy can be obtained,which can be compressed very efficiently by a downstream waveletcompression for example. Furthermore the use of an INTRA coded imageblock MB1 is also advantageous, since decoding errors typicallyoccurring within the sequence of encoded images B1, . . . , BM are notaccepted by an INTRA coded image block MB1 from a previous encoded imageB1, . . . , BM and thereby an image error also does not occur in theassociated decoded image D1, . . . , DM.

Furthermore the start image BSP can be defined on the basis of thedecoded image D3 used, if an evaluation of the encoding properties showsthat a defined number AM of image blocks MP1 of this used, decoded imageD3 were INTRA coded. If for example a number of possible start imagesBSP are available, then through this variant of the method, that startimage BSP is selected by the second encoding method CV2 for the encodingof the image group GOP in which the predeterminable minimum number AM ofINTRA coded image blocks MB1 can be found of the associated decodedimage D1, . . . , DM. This will be explained by the following example.The start image BSP should be selected so that the decoded image usedfor the third output image A3 has at least 20 image blocks MB1, whichwere compressed by the INTRA coding mode. The third or fourth originalimage O3, O4 can be selected as the start image BSP. The decoded imagesassociated with the third and fourth original images O3, O4 are thethird and fourth decoded images D3, D4. In the third decoded image D3,25 INTRA coded image blocks MB1, and in the fourth decoded image D4, 19INTRA coded image blocks MB1 are present. Thus the third original imageO3 is selected as the start image BSP of the second image group GOP2 forencoding the succession of original images O1, . . . , ON.

In a possible further variant of the method, the start image BSP isdefined on the basis of the decoded image D3 used, if an evaluation ofthe encoding property shows that all image blocks MB1 of this used,decoded image D3 were INTRA coded. This is advantageous, since a smalldifference signal with a small signal energy can thus be found for theentire third output image A3. In this case the start point coincideswith an “I”-marked decoded image D1, . . . , DM.

Further it can be necessary, for the determination of the start imageBSP, not only to take into account the coding property K1, but also amaximum number of consecutive original images O1, . . . , ON, wherebythis maximum number may not typically not be exceeded. For example, as aresult of determining the encoding property, the start image BSP of thenext image group to be encoded, e.g. GOP2, should be selected so that animage group to be encoded, e.g. GOP1, should include ten originalimages. The maximum number per image group is however limited to sixoriginal images. Thus for example the current image group GOP1 to beencoded is divided into two subgroups, so that first of all six and thenfour original images are encoded in a relevant image group.

In a variant of the method a number of successive original images O1, .. . , ON of the image group GOP to be encoded can be set, depending onthe encoding property K1 determined. This is explained in greater detailin FIG. 5, with those original images O1, . . . , ON always being usedas a start image BSP on the basis of the determined encoding property K1for example, for which all image blocks MP1 of the associated images D1,. . . , DM are INTRA coded. These decoded images D1, . . . , DM areidentified with an “I”. Initially the first original image 01 is used asthe start image BSP of the first image group GOP1 for encoding of theoriginal images O1, . . . , ON. In this case the output image All andthe intermediate image Z11 are generated. The encoding according to thesecond encoding method CV2 is already aborted after the second originalimage O2. Then, with the third original image O3, a decoded image D3marked with an “I” is available, and thus the encoding property K1indicates that a new start image BSP is to be set here for the secondimage group GOP2. After the second image group GOP2 the third imagegroup GOP3 is encoded, with for example the output image A21 beingcreated. Thus the first image group GOP1 has two and the second imagegroup GOP2 four original images, which are encoded by the secondencoding method CV2.

The exemplary embodiment dealt specifically with the encoding of theoriginal images O3, O4, O5 and O6. The first and the second encodingmethod CV1, CV2 in this case create a number of items of encoded pictureinformation. In this case the encoded picture information for exampleincludes the intermediate images Z1, . . . , Z3, the third output imageA3, the encoded images B3, B4, B5, B6, and the movement vector listsML1, ML, ML3. Other information is also produced during encoding, suchas movement vectors in the first partial band encoding for example. Forencoding of the entire succession of original images O1, . . . , ON, aplurality of encoded picture information is produced in accordance withthe first and second encoding method CV1, CV2, which is created in asimilar fashion to the exemplary embodiment.

FIG. 4 shows an encoding device EV, a decoding device DV and atransmission medium UEM for transmitting information from the encodingdevice EV to the decoding device DV. The encoding device EV includes afirst video encoding module VE1 with the aid of which a succession oforiginal images O1, . . . , ON are created following the first encodingmethod CV1 are generated into a succession of encoded images B1, . . . ,BM and from these are generated a succession of decoded images D1, . . ., DM. Further the decoding device EV includes a second video encodingmodule VE2 for executing the encoding of a succession of original imagesO1, . . . , ON in accordance with the second encoding method CV2, takinginto account the decoded images D1, . . . , DM into intermediate imagesZ1, Z2, Z3, into output images A1, A2, A3 and for creating a number ofmovement vector lists ML1, . . . , ML3. Furthermore the decoding deviceEV has a first storage device S1 which stores different images, such asthe original images O1, . . . , ON, in an organized manner forprocessing. In addition the decoding device EV contains a transmitterunit SE for transmission of encoded picture information, such as theencoded images B1, . . . , BM for example. The transmitter unit SE, thefirst storage device S1, the first video encoding module VE1 and thesecond video encoding module VE2 are connected to each other via a firstconnection network VN1 for exchange of data and control information.

The decoding device DV has a first video decoding module VD1 fordecoding the encoded images B1, . . . , BM, which were created inaccordance with the first encoding method CV1. In addition the decodingdevice DV has a second video encoding module VD2 for decoding thecompressed images created by the second encoding method CV2, such as theintermediate images Z1, Z2, Z3 for example and/or the third output imageA3. In addition the movement vector lists ML1,

ML3 are also used for reconstruction of the original images O3, O4, O5,O6. Furthermore the decoding device DV includes a receiver unit EE, withwhich the encoded picture information such as for example the encodedimages B1, . . . , BM are received and stored in a second storage deviceS2 for further processing. Finally the decoding device DV also containsthe second storage module S2, in which different information and data,such as the movement vector lists ML1, . . . , ML3 are stored. Thereceiver unit EE, the second storage device S2, the first video decodingmodule VD1 and the second video decoding module VD2 are connected toeach other via a second connection network VN2 for exchange of data andcontrol information.

The transmission medium UEM is used for transfer of the encoded pictureinformation from the encoding device EV to the decoding device DV.

The encoding device EV and/or the decoding device DV can be accommodatedin a mobile radio device according to the GSM (Global system for MobileCommunications) or UMTS (Universal Mobile Telecommunications system)standard as well as in a computer unit, which is possibly integratedinto a portable device. To transfer the encoded picture informationbetween the decoding device EV and the decoding device DV a wirelessradio network, in accordance with the GSM standard for example, as wellas a wired transmission medium, such as an IP (Internet Protocol)-basednetwork or ISDN (Integrated Services Digital Network) can be used.

In addition to the option of sending the encoded picture informationfrom the encoding device EV to the decoding device DV, it can beexpedient in practice to store the encoded picture information on astorage medium such as a CD (Compact Disk) or a video server forexample, for subsequent use.

The image decoding method also encompasses a method in which the methodfor encoding a succession of original images O1, . . . , ON can bedecoded. For example the succession of encoded images B1, . . . , BM isinitially decoded through the first video decoding module VD1 into asuccession of decoded images D1, . . . , DM. Subsequently the secondvideo decoding module VD2 uses the intermediate images Z1, Z2, Z3 andthe third output image A3 as well as the assistance of the movementvector list ML1, ML3 and the decoded images D1, . . . , DM to generate asuccession of reconstructed images R1, . . . , RM of the succession oforiginal images O1, . . . , ON.

In a possible variant the reconstructed images R1, . . . , RN which havebeen generated by the second video decoding module VD2 are forwarded toan output medium DD, for example a monitor. As an alternative or inaddition, the decoded images D1, . . . , DM, created by the first videodecoding module VD1, can be reproduced on the monitor. For example thedecoded images D1, . . . , DM exhibit only a reduced image quality,whereas the reconstructed images R1, . . . , RM represent a high-qualityimage. Thus for example the user can select whether a succession ofimages is to be reproduced in a low or in a high image quality on theoutput medium.

A description has been provided with particular reference to exemplaryembodiments thereof and examples, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the claims which may include the phrase “at least one of A, B and C”as an alternative expression that means one or more of A, B and C may beused, contrary to the holding in Superguide v DIRECTV, 358 F3d 870, 69USPQ2d 1865 (Fed. Cir. 2004).

The invention claimed is:
 1. A method for encoding a succession oforiginal images, comprising: creating a succession of decoded imagesfrom the succession of original images based on a first coding method,which is based on a motion-compensated, predictive coding; and before animage encoding of an image group of consecutive original images by asecond coding method, which is based on a motion-compensated, temporallyfiltered subband coding, defining a first image of the image group basedon an identified encoding property of one of the decoded images, whichis used to create an output image of a lower resolution level of theimage group, with at least one output image being generated at eachresolution level by the image encoding of the consecutive originalimages of the image group and of at least one of the decoded images. 2.A method as claimed in claim 1, wherein the first image is defined basedon a used, decoded image if an evaluation of the encoding property showsthat at least one image block of the used, decoded image was INTRAcoded.
 3. A method as claimed in claim 2, wherein the first image isdefined based on the used, decoded image if the evaluation of theencoding property shows that a first predetermined number of imageblocks of the used, decoded image were INTRA coded.
 4. A method asclaimed in claim 3, wherein the first image is defined based on theused, decoded image if the evaluation of the encoding property showsthat all image blocks of the used, decoded image were INTRA coded.
 5. Amethod as claimed in claim 4, wherein a second number of successiveoriginal images of the image group to be encoded are set depending onthe encoding property determined.
 6. A method as claimed in claim 4,wherein at least one intermediate image is created at each resolutionlevel, and wherein the intermediate images and the at least one outputimage of the lower resolution level are compressed.
 7. A method asclaimed in claim 6, wherein compression is performed according to awavelet-based transformation.
 8. A method as claimed in claim 3, whereina second number of successive original images of the image group to beencoded are set depending on the encoding property determined.
 9. Amethod as claimed in claim 3, wherein at least one intermediate image iscreated at each resolution level, and wherein the intermediate imagesand the at least one output image of the lower resolution level arecompressed.
 10. A method as claimed in claim 9, wherein compression isperformed according to a wavelet-based transformation.
 11. A method asclaimed in claim 2, wherein a second number of successive originalimages of the image group to be encoded are set depending on theencoding property determined.
 12. A method as claimed in claim 2,wherein at least one intermediate image is created at each resolutionlevel, and wherein the intermediate images and the at least one outputimage of the lower resolution level are compressed.
 13. A method asclaimed in claim 12, wherein compression is performed according to awavelet-based transformation.
 14. A method as claimed in claim 1,wherein a second number of successive original images of the image groupto be encoded are set depending on the encoding property determined. 15.A method as claimed in claim 1, wherein at least one intermediate imageis created at each resolution level, and wherein the intermediate imagesand the at least one output image of the lower resolution level arecompressed.
 16. A method as claimed in claim 15, wherein compression isperformed according to a wavelet-based transformation.
 17. An imagedecoding method, comprising: decoding at least one image encoded inaccordance with the method as claimed in claim 1, where the at least oneimage includes at least one of an intermediate image and the at leastone output image of the lower resolution level.
 18. A decoding device,comprising: a decoding unit decoding at least one image encoded inaccordance with the method as claimed in claim 1, where the at least oneimage includes at least one of an intermediate image and the at leastone output image of the lower resolution level.
 19. An encoding devicefor encoding a succession of original images, comprising: an encodingunit to execute: creating a succession of decoded images from thesuccession of original images based on a first coding method, which isbased on a motion-compensated, predictive coding; and defining, beforean image encoding of an image group of consecutive original images by asecond coding method, which is based on a motion-compensated, temporallyfiltered subband coding, a first image of the image group based on anidentified encoding property of one of the decoded images, which is usedto create an output image of a lower resolution level of the imagegroup, with at least one output image being generated at each resolutionlevel by the image encoding of the consecutive original images of theimage group and of at least one of the decoded images.